Monitoring the state of the electric power grid for operating anomalies, as well as equipment degradation and failures, is important for the reliable supply of electric energy. Current methods involve monitoring parameters such as voltage, current and relative phase angles of the power system as it operates. These actual values are then applied to an electrical model for analysis. These conventional monitoring methods typically require a steady state operational environment for power systems analysis.
Actual power system measurements, from a subset of all key data points in the power system, are typically captured using a Supervisory Control and Data Acquisition (SCADA) system. Each substation connected to the power grid is equipped with several potential and current transformers to measure voltage, current, and electric power flow on each line and bus. The real-time voltage and current data is transmitted from each substation to a central computer through a remote terminal unit. These acquired readings from throughout the power system and are then processed by a state estimator algorithm to determine a complete set of the most likely values for all key points in a model of the power system. System security applications are run on these models to assess the ability of the power system to recover from various possible disturbances. This security contingency analysis attempts to determine if the power system will return to an equilibrium state or become unstable after selected system disturbances.
One characteristic of power system modeling for conventional security analysis is that the system topology and component parameters must be correct for the results to be meaningful. Inaccuracies in conventional security analysis can occur if data sampled from the actual power system are applied to a model that fails to consider a change in system topology, e.g., an open transmission line in its connectivity topology. Furthermore, inaccuracies in the models used for various power system components, such as transmission lines and power plants, can lead to an inaccurate security analysis.